The present invention relates to improvement of a direct-feed type writing implement having a point assembly as a writing portion at the tip, such as a ball-point pen, felt pen, fountain pen, etc., comprised of an ink tank for direct ink storage, a collector as an adjusting element made up of multiple thin plates(vanes) for adjusting the internal pressure using capillary action, an ink feeder means for feeding ink from the ink tank to the point assembly. The present invention particularly relates to improvement of a collector so as to be adjustive to a sharp change in temperature and pressure.
In order to reduce the occurrence of forward leakage from the writing point and the occurrence of backward leakage smudging clothes and causing writing deficiency due to ink falling during writing with its pen point up, conventionally known oil-based ball-point pens use high viscosity ink, typically ranging from about 3,000 to 10,000 mPaxc2x7sec(milipascalxc2x7second) with a narrow ink tank to obtain enhanced capillarity. Therefore,the conventional oil-based ball-point pens suffers from the problems of heavy writing sensation, blotting, drawn line unevenness during writing and thin density because of their high ink viscosity and its narrow tank.
There have been known so-called sliver type pens which have a sliver of fabric bundles impregnated with a low viscosity ink of some mPaxc2x7sec and an ink feed for feeding ink to their pen point. This sliver type pen, however, has the problem of ink consumption being indiscernible and the problem of the drawn line being unstable such that an ample amount of ink flows out and hence thick drawn lines can be obtained in the starting stage and the amount of ink gradually become lower and hence the drawn lines become thinner as the ink is consumed for writing. To deal with this, the capillary capacity of the sliver may be set to be low so as to smoothly deliver the ink from the sliver. However, this setting will increase the occurrence of ink eruption from the sliver and smudging clothes due to impacts such as from being dropped. In contrast, if the capillary capacity of the sliver is increased, there occurs an ink ejection problem in that the ink flow rate sharply lowers as the ink is used for writing and the drawn line becomes considerably thin in the latter half of the pen""s life even though there is still an abundant amount of ink left.
In order to solve the drawbacks of the oil-based ball-point pen and sliver type writing implement described above, a so-called direct ink storage type writing implement using a collector(to be referred to hereinbelow as a collector type writing implement) has been known. This collector type writing implement, as shown in FIG. 1, has an ink tank 3 for directly storing ink 2 arranged in the rear half and mechanism, which has been used in fountain pens, for adjusting the inner pressure by air replacement during writing, using a collector 6 having many retaining grooves 13 defined by vanes(thin plates). A collector type writing implement has advantages that it delivers ink 2 at a flow rate equal to or above that of a sliver type writing implement at the starting stage and will not reduce its ink flow rate and is able to provide thick lines even without applying any extra writing force until its life""s end(inkend). However,since the writing implement of this type needs a greater amount of ink as the load than the oil-based ball-point pen, it has a large-diametric ink tank 3 holding a relatively large amount of ink 2(typically about 1 to 3 cc).
In the collector type writing implement, ink 2 moves between collector 6 and ink tank 3 (or air comes in and out through a narrow ink channel 14) when the atmospheric pressure varies, so as to adjust the internal pressure whereby ink 2 will not leak out from the tip, designated at 9, of a point assembly 1.
In this collector writing implement, generally a cap 17 which hermetically seals both the air hole, designated at 10, and point assembly 1, by its having annular undercut shaping is provided in order to prevent evaporation of ink 2. However, this cap 17 has a drawback called pumping phenomenon that the internal pressure within cap 17 will change when this cap 17 is put on and off, to thereby cause ink 2 to gradually fill up the collector 6 and at last ink 2 will flow out from air hole 10 exceeding the collector""s retaining limit.
Further, the collector typewriting implement has another drawback that ink eruption which is attributed to the same mechanism as above, occurs with repeated increase and decrease in pressure due to temperature variations, changes pressure in airplane, difference in elevation or the like. It is possible to solve the pumping phenomenon by providing a movable inner cap 18 for cap 17 or by providing a seal face of a rubber end face(not shown), or some other manipulation. On the other hand, in order to solve the eruption problem due to repeated increase and decrease in atmospheric pressure, it is necessary to enlarge the maximum ink retaining capacity of collector 6 (enlarge the diameter or length of the collector) or to reduce the volume of ink tank 3. However, enlargement of the barrel size makes its appearance unstylish, reduction of the ink stored in ink tank 3 makes the pen""s life short and hence degrades its cost performance. With a too long collector 6, the ink head at tip 9 of point assembly 1 would become too high, easily causing forward leakage. If the above problem is tried to be solved by modifying ink 2, an ink with markedly poor wettability should be adopted compromising the writing comfort.
If a collector type writing implement which has had cap 17 put on under approximately 1 atm. at the ground level, is carried on an airplane in which the pressure is generally. adjusted to about 0.8 atm., a pressure imbalance will occur. That is, if cap 17 is put off in the airplane, the interior space of the pen at 1 atm., is incidentally exposed to the onboard air of 0.8 atm., so that ink 2 inside rushes through the air channel, designated at 15, inside collector 6 and erupts out from air hole 10 at the front end without ink 2 being able to be retained in retaining grooves 13 of collector 6.
In order to solve this eruption problem originated from pressure imbalance, Japanese Utility Model Publication Hei 3 No.31580 and Japanese Utility Model Publication Hei 3 No.31581 have disclosed devices. In these disclosures, one retaining groove at the middle portion of the collector has two air channels or cutouts symmetrically arranged at different positions on the collector periphery from the air channels of the neighboring retaining grooves, so that the rushing ink will branch into the left and right channels to thereby prevent the ink from directly flowing out through the air hole.
However, with these devices, if ink reaches the vane with two cutouts for the ink retaining groove in question when the internal pressure is adjusted moderately in the normal situation, it becomes impossible to perform air replacement and part of the vane having two cutouts, located opposite the ink channel, becomes unable to retain ink. Resultantly, the retained amount of ink 2 becomes reduced. Further, if only one of the retaining grooves in the middle part has this configuration, ink cannot be retained by the retaining grooves located from that position to the rear of the barrel when a sharp pressure change occurs in an airplane. That is, this configuration is able to lessen the rushing of ink to a certain degree at that site, but cannot retain the whole ink and results in failure to prevent ink from erupting.
It might be considered that such retaining grooves with two cutouts as above can be provided at a number of sites. In this case, however, the above-mentioned part incapable of holding ink also multiplies, so that the retainable volume of ink during moderate adjustment of pressure in the normal situation is reduced. Resultantly, a greater collector may be needed, which leads to the necessity of a large-diametric barrel or reduction in ink load amount which may make the life of the writing implement short.
In order to solve the problem of this ink retaining efficiency, Japanese Patent Application Laid-Open Hei 9 No.104194 offers an invention. In this disclosure, a partitioning plate is provided between the ink channel (called xe2x80x98air/liquid exchange channelxe2x80x99 in the application of the invention but will be referred to here as the ink channel) and the air channel(side channel) to separate one from the other. When inkenters the internal space of the collector(pen core), the ink retaining grooves(collector grooves) are filled with ink gradually in circular direction from one end where the ink channel is located toward the other end.
In the invention of the above disclosure, when the cap is put on and off under circumstances where the ambient pressure varies, ink flushes through the air channel. That is, this configuration has the same problem as the above two devices (disclosed in Utility Model Publication Hei 3 No.31580 and Japanese Utility Model Publication Hei 3 No.31581) or the problem that ink floods out without making efficient use of the retention capacity of the collector.
Further, with the configuration of the above disclosure, if the air channel side is wetted with ink due to rushing ink or ink scattering which may be caused by impacts when the pen is dropped, most of the retaining grooves become sealed by ink from both sides, the narrow vertical groove side, i.e., ink channel side and the air channel side because the retaining grooves are configured so as to allow ink to flow in only one direction when they hold ink. Thus, the air channel is blocked by the ink so that proper replacement of air in the retaining grooves cannot be performed. This means that the collector cannot provide the function as the adjustor any longer, easily causing eruption and forward leakage.
When the above-described writing implement shown in FIG. 1 is put under circumstances where the ambient pressure varies, a strong pressure may act inside the point assembly 1 so that ink 2 may leak forwards from tip 9 of point assembly 1, beside the rushing of ink 2 into collector 6. Therefore, there has been a demand for a device which avoids the pressure inside point assembly 1 directly acting on tip 9 of the writing point when the ambient pressure varies.
It is a primary object of the present invention to improve a prevalent, collector type writing implement, and provide a collector for a writing implement which meets the demand for improvement in deficiency prevention performance such as the capability of preventing ink leakage from occurring due to influence of the ambient pressure being varied during usage or when its cap is put on and off, the capability of preventing ink from erupting or leaking forward when the implement has been stored at a shop for a long period, and which still provides smooth writing comfort during writing. In particular, the object of the present invention is to prevent drawbacks such as ink eruption, which would be caused by repeated increase and decrease in pressure such as repeated flights of airplane whilst meeting the demands for a slim appearance of a collector type writing implement which is liable to be thick, without compromising excellent writing comfort of the conventional collector type writing implement and without increasing the cost.
According to the present invention, a writing implement collector for adjusting the internal pressure of a writing implement having a point assembly with a writing point at the tip thereof, an ink tank for storing a relatively low viscosity ink, and a feeder means for feeding ink from the ink tank to the writing point, the collector comprising: a multiple number of plate-like elements defining ink retaining grooves therebetween; an ink channel extending through the multiple number of plate-like elements in the axial direction of the collector for connecting the ink retaining grooves; an air channel defined by the arrangement of the multiple number of plate-like elements with cutouts or slots, wherein ink is introduced through the ink channel by the function of capillary action and temporarily held in the ink retaining grooves while air passage in the axial direction and radial direction is secured by the combination of the air channel and retaining grooves, and is characterized in that the air channel is continuously formed along the collector axis, zigzagging with a multiple number of turns of direction.
In the present invention, the air channel of the first configuration is formed on the side opposite to the ink channel with respect to the axis of the collector.
In the present invention, the air channel of the second configuration is formed on the same side as the ink channel with respect to the axis of the collector.
In the present invention, the air channel of the third configuration is formed on the same side as, and on the side opposite, the ink channel with respect to the axis of the collector.
In the present invention, the air channel is comprised of multiple linear channel parts each extending in the axial direction of the collector but adjacent parts being arranged different angular positions with respect to the axis of the collector while each plate-like element located at the boundary between adjacent linear channel parts has a cutout for defining a connecting groove for establishing communication between the adjacent linear channel parts.
In the present invention, the collector is divided into multiple blocks in the axial direction thereof, each block forming an air channel while each plate-like element located between blocks, excepting the part around the ink channel, have an outside diameter smaller than that of the adjacent plate-like elements so as to form a connecting passage which establishes communication between the air channels of the adjacent blocks.
In the present invention, the air channel is configured by providing only one cutout or slot on the periphery of each plate-like element.
In the present invention, a communication hole for establishing communication with the feeder means is formed in, at least, one ink retaining groove.
In the present invention, the ink tank directly stores therein a relatively low-viscosity ink having a viscosity of 2 to 100 mPaxc2x7sec at normal temperature.
Specifically, the writing implement of the present invention is applicable to a ball-point pen having a point assembly with a writing point at the tip thereof and an ink feeder means using capillary action for creating passage of ink from an ink tank to the tip of the writing point, or a felt pen or marker with its ink feed itself serves as a writing point. Arranged between a cup-like ink tank with a bottom and the writing point is a collector, which has a vent slot and air channel connected to the outside, a narrow and long ink channel serving as air/liquid exchanger groove and an appropriate number of retaining grooves defined by vanes (thin plate-like elements) spaced a predetermined distance apart from each other and provides the function of adjusting the internal pressure inside the pen body, by making ink 2 flow in and out of the retaining grooves.
As an effective means of the present invention in order to alleviate ink eruption due to rushing of ink from the ink tank to the collector retaining grooves when a sharp change in temperature or pressure occurs, the first configuration of an air channel is defined by forming cutouts (or slots) at the periphery of the collector on the side opposite to the ink channel (on the opposite side with respect to the axis of the collector) and by making turns of direction at least twice so that adjoining air channel parts are not aligned on one straight line parallel with the axis. Preferably, the air channel is made turning at least three times so that the collector is divided into four blocks A, B, C and D or more.
The configuration, as the air channel of the above first means, where the air channel of the collector is defined by forming one cutout (or slot) only in the half section opposite to the ink channel with respect to the collector axis, is effective in maintaining the collector function even if the air channel is wetted by rushing ink, by making full use of the capability of the retaining grooves. Further, when a collector 106 is formed by injection molding using a plastic, for example, there is no need to change the metal die structure of the metal die for forming the side opposite to an ink channel 114 because air channel 115 needs to be winded in zigzag from one part to another by shaping only the half section as in the conventional configuration. Therefore, it is possible to exactly mold thin fin-like vanes 112 without changing the metal die structure and retaining grooves 113 in the same manner as the prior art without the necessity of extra parts cost.
As another effective means of the present invention in order to alleviate ink eruption due to rushing of ink from the ink tank to the collector retaining grooves when a sharp change in temperature or pressure occurs, the second configuration of an air channel for communication with the outside air is defined so as to wind making multiple turns of direction by forming cutouts(or slots) in the same half side where the ink channel is formed (on the same side with respect to the axis of the collector) at the periphery of the section and by deflecting (connecting) one axial air channel part (215a, 215b, 215c, . . . ) for each block with the adjoining axial air groove using a connecting passage (222a, 222b, 222c. . . ), which is defined by a plate-like element having an outside diameter smaller than that of the adjacent vanes so that the adjoining air channel parts are not aligned on one straight line parallel with the axis. Preferably, the air channel is made zigzag(winding) at least three times so that the collector is divided into four blocks A, B, C and D or more(see FIG. 9 for example).
The plate-like elements defining the connecting passages (222a, 222b, 222c) at their periphery are made smaller in diameter than the adjacent plate-like elements (vanes) so as to create an air channel along almost full circumference. This configuration is effective in maintaining the collector function even if the air channel is wetted by rushing ink, by making full use of the capability of the retaining grooves. Further, when the collector is formed by injection molding using a plastic, for example, the pattern needs to be formed only on the same side of the ink channel of the collector, therefore the metal die of the half side on the side opposite to the ink channel is easily formed. Therefore, it is possible to exactly mold thin fin-like vanes without changing the metal die structure and retaining grooves in the same manner as the prior art without the necessity of extra parts cost.
As still another effective means of the present invention in order to alleviate ink eruption due to rushing of ink from the ink tank to the collector retaining grooves when a sharp change in temperature or pressure occurs, the third configuration of an air channel for communication with the outside air is defined so as to wind making multiple turns of direction by forming each block with cutouts (or slots) (315a, 315b, 315c . . . ) and arranging the cutouts alternately at the position in proximity to the ink channel and at the position on the side opposite to the ink channel with the center of the ink channel in between, and by deflecting at least twice (connecting) one axial air channel part (315a, 315b, 315c, . . . ) for each block with the adjoining axial air channel parts using a connecting passage (322a, 322b, 322c . . . ) which is defined by a plate-like element having an outside diameter smaller than that of the adjacent vanes so that the adjoining air channel parts are not aligned on one straight line parallel with the axis. Preferably, the air channel is made turning(winding) at least three times so that the collector is divided into four blocks A, B, C and D or more.
Further, the configuration of the present invention, in which a communication hole for establishing communication with the intermediate cores 7 and 8 is formed in, at least, one ink retaining groove, is able to prevent ink seepage from the writing point under a varying pressure situation. If the size Tr of the conduit hole is too small, there occurs the risk that ink may be sucked from the interior to the retaining groove side because of capillarity imbalance. Therefore, the conduit hole preferably has a dimension greater than the width t of the smallest retaining groove (Tr greater than t).
Here, the components used in the present invention may be conventionally publicly known items. For example, as the ink, a pseudo-plastic ink (also called gel ink) which has a low (or medium) viscosity of 2 to 100 mPaxc2x7sec at normal temperature (about 23xc2x0 C.) and presents a rather high viscosity in the static state so as to prevent forward leakage of ink from the tip of the point assembly and lowers its viscosity when affected by shearing force or movement while writing so as to enable smooth writing, may be used by modifying it to have a lower viscosity to some degree. A typical solvent as the base of the ink is water but organic solvent such lower alcohols, higher alcohols, xylene, etc., glycols such as ethylene glycol, and their esters, which are publicly known as usable for collector type writing implements, may be used as appropriate for the ink.
Similarly, for other components, conventionally used items can be selected as appropriate, such that the ink feeder means for the center core (serving as a writing point in the case of a felt pen or marker) may be of a fiber bundle core made up of fabric threads shaped by heat or adhesives, of a plastic core formed by extrusion molding having a snow-crystal section, of a sintered core made up of small particles with spaces or pores therein, thermally fixed or bonded with adhesives, or of a sponge, as long as it is capable of holding and leading ink to a certain degree or more.